AuthorisedTherapeutic confirmatory (Phase III)Interventional

A Phase 3 randomized, double-blind, placebo-controlled, parallel group, multicenter study with open-label extension to evaluate the efficacy and safety of fenfluramine hydrochloride in study participants with Rett syndrome

This research study is investigating a new oral medicine called Fintepla (fenfluramine hydrochloride) for individuals living with Rett syndrome. The main goal is to find out if this medicine can improve symptoms of Rett syndrome and if it is safe to use. Participants will be divided into two groups: one group will receive Fintepla, and the other will receive a dummy medicine that looks the same but contains no active drug. This comparison helps researchers understand the medicine's true effects. The study will look at changes in behaviour and overall well-being over 14 weeks. There's also an option to continue taking the active medicine after the initial comparison phase. This type of study, called a Phase 3 trial, is a crucial step in determining if new treatments can be approved for wider use.

At a glance

Status

Authorised

Phase

Therapeutic confirmatory (Phase III)

Sponsor

UCB Biosciences Inc.

Enrolment target

Start

15 Apr 2026

Rett syndrome

What is this study about?

This study is a research project focusing on a new medicine, Fintepla, for people with Rett syndrome. Rett syndrome is a rare genetic (inherited) condition that affects brain development, leading to problems with movement, communication, and other abilities, often more severely in girls.

The main purpose of this study is to see if Fintepla can help reduce some of the challenges associated with Rett syndrome and if it is safe to use. Researchers are particularly interested in how the medicine affects behaviour and general well-being. To do this, some participants will receive the active medicine, while others will receive a 'placebo', which is a dummy medicine that looks identical but contains no active drug. This allows the researchers to fairly compare the effects of Fintepla against not taking the active medicine at all. Because neither the participants nor the doctors will know who is getting which treatment, it helps ensure the results are unbiased.

This is a 'Phase 3' study, which means it's one of the final steps in testing a new medicine before it can be considered for approval for wider use. If the results show that Fintepla is both effective and safe, it could potentially become a new treatment option for individuals with Rett syndrome.

Key takeaways

This study is testing a new liquid medicine called Fintepla for Rett syndrome.
It aims to see if Fintepla helps with symptoms and is safe to use.
Participants will receive either Fintepla or a dummy medicine, with neither they nor their doctors knowing which one.
The study lasts 14 weeks, with potential for an extended period where all receive active medicine.
Heart health will be closely monitored throughout the study.
It's a Phase 3 study, meaning it's a key step before potential wider availability.

Who may be eligible?

To join this study, people need to have a confirmed diagnosis of Rett syndrome. The study is open to both men and women.

Participants must be 18 years old or older. There is no upper age limit for taking part.

There might be other specific health requirements or conditions that would make someone suitable or unsuitable for the study, but these details are not fully provided here. A doctor or study staff would check all these criteria carefully to make sure the study is right for each person.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Do I have a diagnosis of Rett syndrome?
Am I, or the person I care for, 18 years old or older?
Am I able to take medicine by mouth (oral solution)?
Am I willing to attend regular clinic visits for health checks and assessments, including heart checks?

Answer every question to see your result.

What does participation involve?

If you join this study, you'll be involved for about 14 weeks, with an option to continue longer. During this time, you will visit the study clinic regularly. At these visits, doctors and nurses will carry out various checks and assessments, including answering questionnaires about your or your child's behaviour, sleep, and communication. These questionnaires will help doctors understand if the medicine is making a difference.

You will be given either the study medicine, Fintepla oral solution, or a matching placebo (a dummy medicine) to take regularly, as instructed. Neither you nor your study doctor will know which one you are taking until the end of the initial 14-week period. Your heart will be regularly checked with an ECG (a simple test that records your heart’s electrical activity) and an echocardiogram (a scan of your heart), as some medicines can affect the heart. Blood tests and other health checks will also be done to monitor your safety and the medication's effects. After the initial 14 weeks, participants may have the option to enter an 'open-label extension', where everyone receives the active Fintepla medicine.

Potential risks and benefits

Taking part in a clinical study can offer potential benefits, such as access to a new medicine before it is widely available, and careful monitoring of your health by medical professionals. It's important to remember that since this is a research study, we don't yet know if Fintepla will definitely help with Rett syndrome. There are also potential risks; all medicines can have side effects, and some may be serious. The study team will closely monitor participants for any unwanted effects both during and after taking the medicine, especially effects on the heart. You will receive detailed information about all known and potential side effects before deciding to join. Taking part is completely voluntary, and you have the right to withdraw from the study at any time, for any reason, without it affecting your medical care.

Locations (7)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

—
Unverified
Spain
—
Unverified
Poland
—
Unverified
France
—
Unverified
Hungary
—
Unverified
Belgium
—
Unverified
Italy
—
Unverified
Germany

Common questions

What is Fintepla?

Fintepla is the name of the medicine being tested in this study. It's an oral solution, meaning it's a liquid you take by mouth.

What is a 'placebo'?

A placebo is a dummy medicine that looks exactly like the real medicine but contains no active drug. It helps researchers compare the effects of the active medicine fairly.

Why don't I know if I'm getting the real medicine or the placebo?

This is called a 'double-blind' study. Neither you nor your doctor will know who is getting which treatment. This helps ensure the study results are accurate and unbiased.

How long will I be in the study?

The main part of the study lasts for 14 weeks. After that, there might be an option to continue in an extension phase where everyone receives the active medicine.

Will my heart be checked?

Yes, your heart will be carefully monitored throughout the study with tests like ECGs and echocardiograms. This is a standard safety measure for this type of medication.